LOS ANGELES -- The offices of DoubleLine Capital are filled with fine art, featuring works from Mondrian, Warhol, Picasso and Van Gogh. But it's the painting hanging just beside the elevator door, by Jeffrey Gundlach, that's the most significant.

That painting, the asset management firm's marquee sign, was painted in oil and lettered without a stencil by Gundlach, the company's founder. The painting is done in the same straight-lines-bold-primary-colors style of Mondrian, one of Gundlach's favorite artists and an inspiration for the name of the firm.

The fact that Gundlach, not trained in art, grabbed oil paints and a canvas to paint the company's sign is symbolic of the way he created the company nearly four years ago. Forced out of his bond-management job at his employer of 23 years, TCW, Gundlach found himself into the role of not just managing money, but running a business, too. All the while, TCW and DoubleLine were entangled in legal battles for months, lawsuits which are now settled.

Picking up new skills, down to painting the office's sign, is part of Gundlach's work in progress. "We were basically forced to start our own company overnight," Gundlach says. "We learned as we went along. I never had to deal with the formulation of a company. … I only really knew about 60% maybe of the totality of what it took to run a company, but we basically learned the other 40% over about a three-month time period."

Gundlach likes to joke with colleagues that he got the lines straighter on his painting than Mondrian did in many of his, but, it could be said that he's also learned how to run an asset management company better than some of the more established players. A big test could be looming, though, as the threat of higher interest rates poses the danger of knocking bond prices down.

Nonetheless, DoubleLine now has roughly $60 billion under management in a variety of investment products, including its six mutual funds, making it arguably one of the fastest-growing investment management firms in history. The firm's genesis was unusual in that it has a "very long track record" at TCW, helping the company past the hurdle of getting investors' attention. Even so, the firm's growth has pleased Gundlach, who says he would have said reaching $50 billion in assets in three years would have been a solid "stretch goal."

Breaking out from the pack in the crowded investment management industry required some savvy business and management moves, including:

• Moving fast is better than being too slow to avoid mistakes. DoubleLine didn't waste much time getting its products out. It launched its first two mutual funds on April 6, 2010, 123 days after Gundlach was dismissed from TCW. A big reason was that DoubleLine spent more than average to get the process moving, which requires getting regulatory approval and putting the technology systems in place.

"We didn't take the lowest-cost route. We spent substantially more than average, because we were trying to make it work in a compressed time frame," Gundlach says. Spending more wasn't a mistake, because "we felt we needed to get our products in the market fairly quickly before investors lost interest in them and sort of forgot about us."

• Creating a positive work environment. While it might be trendy for other business leaders to rule with fear or paranoia, Gundlach disagrees. Perhaps it's a function that the original 45 employees, all of whom left jobs at TCW, had plenty to worry about already. Those employees weren't drawing salaries in the early days, and the threat of the lawsuit from the old firm was an overhang.

But Gundlach says, "I don't believe in keeping employees edgy or unhappy," he says. "You try to be positive about what they are doing." Employees shouldn't "exactly dread Monday morning and root for Friday afternoon." Keeping employees motivated has been critical, as it took a year for the company to turn a profit.

• Preventing the company from competing with itself. At TCW, Gundlach was dismayed to see how different units of the company did related things and competed with each other. At DoubleLine, Gundlach avoids inter-department battles, as they spread resources thin and confuse and frustrate employees, he says.

At the firm he was at before, "You were really competing with your own firm for shelf space, distribution," he says. "I found that to be incredibly unhealthy and antithetical to growth." At DoubleLine, the company backs its core funds and supports them wholeheartedly. "We try to develop them (investment products) to be as strong as they can be in the particular category."

• Avoiding the temptation to think about failure. As a money manager, Gundlach is well-known for thinking through all possible scenarios, including negative ones, to protect investors from losses. But when starting DoubleLine, he didn't let ideas of failure even enter his mind.

"I never thought that we would fail … I didn't even entertain the idea of failure, because it's just not a productive activity," he says. "Every minute that you spend fretting over success or failure is a minute that you're not working the business."